This standard specifies the random input driving test method for automobile ride comfort. This standard is applicable to various types of automobiles. GB/T 4970-1996 Random input driving test method for automobile ride comfort GB/T4970-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Method of random input running test-Automotive ride comfort
1 Subject and scope of application
This standard specifies the random input running test method for automotive ride comfort. This standard is applicable to all types of vehicles.
2 Referenced standards
GB/T13441 Specification for measurement of human whole-body vibration environment GB/T12534 General rules for road test methods for automobiles GB7031 Method for expressing vehicle vibration input road surface flatness 3 Test conditions
3.1 Road
GB/T4970-1996
Replaces GB4970-85
The test road should be straight, with a longitudinal slope of no more than 1%, a dry road surface, uniform unevenness without sudden changes, and a length of no less than 3km. There should be a 30-50m steady speed section at both ends.
The test road includes two types:
a. Asphalt road, its pavement grade shall comply with the B-grade pavement specified in GB7031; gravel road, its pavement grade shall comply with the C-grade pavement specified in GB7031; b.
Gravel road is the preferred pavement for off-road vehicles and mining dump trucks, and asphalt road is the preferred pavement for other types of vehicles. 3.2 Wind speed
Not more than 5m/s.
3.3 Technical condition of vehicle
3.3.1 All assemblies, parts, accessories and auxiliary devices of the vehicle (including on-board tools and spare tires) must be fully equipped as required and installed in the specified positions. The adjustment condition shall comply with the provisions of the vehicle's technical conditions. 3.3.2 The tire pressure shall comply with the provisions of the vehicle's technical conditions, with an error of no more than ±10kPa. 3.4 Load of vehicle
The load of the vehicle is the rated maximum load mass, which can be increased to half load or empty load as needed. The load is evenly distributed and firmly fixed. It shall not shake or shake during the test, and its quality shall not be changed due to moisture, loss, etc. 3.5 Load of person-seat system
3.5.1 The load of the test part shall be a natural person with a height of 1.70±0.05m and a weight of 65±5kg. 3.5.2 The load of non-test parts shall comply with the relevant provisions of Table 1 in GB/T12534. 3.6 Person's sitting postureWww.bzxZ.net
The occupant of the test part shall relax his whole body, with both hands naturally placed on his thighs, and the driver's hands naturally placed on the steering wheel. The sitting posture shall remain unchanged during the test. In general, the occupant naturally leans on the backrest, otherwise it should be noted. 3.7 Test vehicle speed
The test vehicle speed shall include at least three speeds, including greater than the common vehicle speed, less than the common vehicle speed and the common vehicle speed. During the test, the common gear should be used.
3.7.1 Asphalt road
a. Passenger cars: 40, 50, 60, 70, 80, 90, 100 km/h, the common speed is 70 km/h; b. Other types of cars: 40, 50, 60, 70, 80 km/h, the common speed is 60 km/h. 3.7.2 Gravel road
a. Passenger cars: 40, 50, 60, 70 km/h, the common speed is 60 km/h; b. Other types of cars: 30, 40, 50, 60 km/h, the common speed is 50 km/h. 3.7.3 Speed ​​deviation
The speed deviation is 4% of the test speed.
4 Test instrument
The instrument system for the ride comfort test should include an acceleration sensor, an amplifier, a tape recorder or a data processor. Among them, the signal-to-noise ratio of the tape recorder should be better than 40dB. The performance of the test system should be stable and reliable. The frequency response of the human-seat system is 0.1~100Hz, and the frequency response of the cargo compartment is 0.3~500Hz.
5 Test method
5.1 The acceleration sensor is installed in the following test positions: a. sedan: on the left front and rear seats; b. bus: on the driver's seat, the seat above the left rear axle and the last row of seats; c. other types of cars: on the driver's seat, the center of the compartment floor and 300mm away from the compartment side panel and the rear panel. The acceleration sensor installed on the seat should be able to measure vibration in three directions to measure the acceleration time history of vertical vibration (i.e., linear vibration in the axial direction) and lateral vibration (i.e., linear vibration in the Y-axis direction in the left and right directions and the X-axis direction between the front and rear directions). The sensor should be in close contact with the human body, and a pad for installing the sensor should be placed between the human body and the seat. The chassis is recommended to adopt the structural type shown in Appendix B (reference part).
5.2 During the test, the vehicle shall maintain a steady speed in the steady speed section, and then drive through the test section at a constant speed at the specified speed. When entering the test section, start the test instrument to measure the acceleration time history of each test part, and measure the time of passing the test section to calculate the average speed. 5.3 The sample record length shall not be less than 3 minutes.
6 Ride comfort evaluation
6.7 Evaluation index. For the evaluation of human body vibration, the weighted acceleration root mean square value aw is used, and the weighted acceleration root mean square value of vibration in the vertical direction, left and right direction, and front and rear direction is represented by azw, arw, and axw respectively. Or the sum of the weighted acceleration root mean square value of the three-axis weighted acceleration root mean square value, that is, the total weighted acceleration root mean square value, is represented by wo. For the evaluation of truck compartment vibration, the acceleration root mean square value atm and the acceleration power spectrum density function are used. The meaning and calculation of the evaluation index refer to Appendix A (Supplement)). Note: If the human vibration evaluation index measured is an equivalent mean value, it should be converted into a weighted acceleration root mean square value according to the formula given in Appendix A (Supplement). 6.2 The vehicle ride comfort is evaluated by the relationship curve between the evaluation index and the vehicle speed - the vehicle speed characteristic. 6.3 As required, the ride comfort can also be evaluated by only the evaluation index of the common vehicle speed. 7 Data processing requirements
7.1 The following parameters are used for the human-chair system: a. Cutoff frequency fc 100Hz;
Sampling time interval At = 0.005s;
GB/T 4970-1996
Resolution bandwidth △f and number of independent samples 9: Af = 0.1953Hz, 925; d.
Use window function.
7.2 For truck compartments, it is recommended that the cutoff frequency fc = 500Hz, and other parameters should also be changed accordingly. 8
Contents of the test report
The test report shall include the following contents.
Automobile model, engine number, chassis number, manufacturer. 8.1
Test date.
Automobile parameters:
Maximum total mass, axle load (front axle, rear axle); tire type and size;
Tire pressure (front wheel, rear wheel)
Wheelbase;
Suspension type;
Seat type.
Human parameters:
Gender;
Weight:
Height;
Description of riding posture.
8.5Test instrument model and performance indicators.
8.6Description of the test site, road surface and climatic conditions8.7Test results and analysis. The test results shall indicate the name of the window function. 8.8Test participants and reporters.
8.9 Report date.
A Weighted RMS acceleration
GB/T 4970—1996
Appendix A
Meaning and calculation of smoothness evaluation index
(Supplement)
The weighted RMS acceleration is calculated by weight according to the vibration direction and the sensitivity of the human body to the vibration frequency, and is an evaluation index of human vibration.
A1.1 Single-axis weighted RMS acceleration aw. a Acceleration autopower spectral density function G obtained by equal bandwidth spectrum analysis. (f) Calculate αw. First, calculate the 1/3 octave band acceleration root mean square spectrum value according to the following formula: -
Wherein: α,—
fi,fa,
Gu(f)-
The 1st, 2nd, 3rd
Ga(f)dj
20) 1/3 octave band acceleration root mean square spectrum value with center frequency f, m/s; respectively, the lower and upper frequency of the 1/3 octave band with center frequency f, (see Table A1), Hz; the acceleration self-power spectrum density function of equal bandwidth, m\/s. Then, calculate aw according to the following formula:
The single-axis weighted acceleration root mean square value, m/s; Wherein: aw—
The weighting coefficient of the jth 1/3 octave band, see Table A2. In addition, it can also be obtained from G. (f) Directly integrate and calculate aw: w
Where: w(f)
Frequency weighting function:
Z-axis direction W(f)-
（8/f
X,Y-axis direction W(f)
wz(f) . G.(f)d
(0. 9>f≤4)
(4>f≤8)
(0. 9
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